In the lithography technology, a highlight is recently put on the organic solvent development again. It would be desirable if a very fine hole pattern, which is not achievable with the positive tone, is resolvable through negative tone exposure. To this end, a positive resist composition featuring a high resolution is subjected to organic solvent development to form a negative pattern. An attempt to double a resolution by combining two developments, alkaline development and organic solvent development is under study.
As the ArF resist composition for negative tone development with organic solvent, positive ArF resist compositions of the prior art design may be used. Such pattern forming processes are described in Patent Documents 1 to 3. These patent documents disclose resist compositions for organic solvent development comprising a copolymer of hydroxyadamantane methacrylate, a copolymer of norbornane lactone methacrylate, and a copolymer of methacrylate having acidic groups including carboxyl, sulfo, phenol and thiol groups substituted with two or more acid labile groups, and pattern forming processes using the same.
Further, Patent Document 4 discloses a process for forming a pattern through organic solvent development in which a protective film is applied onto a resist film. Patent Document 5 discloses a topcoatless process for forming a pattern through organic solvent development in which an additive is added to a resist composition so that the additive may segregate at the resist film surface after spin coating to provide the surface with improved water repellency.
Citation List
Patent Document 1: JP-A 2008-281974
Patent Document 2: JP-A 2008-281975
Patent Document 3: JP 4554665
Patent Document 4: JP-A 2008-309878
Patent Document 5: JP-A 2008-309879